Untangling the Galaxy. III. Photometric Search for Pre-main-sequence Stars with Deep Learning

Abstract A reliable census of pre-main-sequence stars with known ages is critical to our understanding of early stellar evolution, but historically there has been difficulty in separating such stars from the field. We present a trained neural network model, Sagitta, that relies on Gaia DR2 and 2 Micron All-Sky Survey photometry to identify pre-main-sequence stars and to derive their age estimates. Our model successfully recovers populations and stellar properties associated with known star-forming regions up to five kpc. Furthermore, it allows for a detailed look at the star-forming history of the solar neighborhood, particularly at age ranges to which we were not previously sensitive. In particular, we observe several bubbles in the distribution of stars, the most notable of which is a ring of stars associated with the Local Bubble, which may have common origins with Gould’s Belt.

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Redshift measurement through star formation

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833046 ◽

2019 ◽

Vol 629 ◽

pp. A7

Author(s):

Mikkel O. Lindholmer ◽

Kevin A. Pimbblet

Keyword(s):

Star Formation ◽

Galaxy Clusters ◽

Main Sequence ◽

Formation Rate ◽

Sloan Digital Sky Survey ◽

X Ray ◽

Star Forming ◽

Sky Survey ◽

The Galaxy ◽

Galaxy Population

In this work we use the property that, on average, star formation rate increases with redshift for objects with the same mass – the so called galaxy main sequence – to measure the redshift of galaxy clusters. We use the fact that the general galaxy population forms both a quenched and a star-forming sequence, and we locate these ridges in the SFR–M⋆ plane with galaxies taken from the Sloan Digital Sky Survey in discrete redshift bins. We fitted the evolution of the galaxy main sequence with redshift using a new method and then subsequently apply our method to a suite of X-ray selected galaxy clusters in an attempt to create a new distance measurement to clusters based on their galaxy main sequence. We demonstrate that although it is possible in several galaxy clusters to measure the main sequences, the derived distance and redshift from our galaxy main sequence fitting technique has an accuracy of σz = ±0.017 ⋅ (z + 1) and is only accurate up to z ≈ 0.2.

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The extended solar neighborhood: precision astrometry from the Pan-STARRS 1 3π Survey

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308020139 ◽

2007 ◽

Vol 3 (S248) ◽

pp. 553-559 ◽

Cited By ~ 4

Author(s):

E. A. Magnier ◽

M. Liu ◽

D. G. Monet ◽

K. C. Chambers

Keyword(s):

Solar Neighborhood ◽

Dynamical Structure ◽

Nearby Star ◽

Stellar Objects ◽

Star Forming ◽

Star Forming Regions ◽

The Galaxy ◽

Low Mass ◽

Single Epoch ◽

Insight Into

AbstractThe Pan-STARRS pathfinding telescope PS1 will begin a major set of surveys starting in 2008, and lasting for 3.5 years. One of these, the PS1 3π Survey, will repeatedly observe the entire sky north of −30 degrees, visiting every position 12 times in each of 5 filters. With single-epoch astrometry of 10 milliarcseconds, these observations will yield parallaxes for stars within 100 pc and proper motions out to several hundred pc. The result will be an unprecedented view on nearby stellar populations and insight into the dynamical structure of the local portions of the Galaxy. One exciting science product will be a volume-limited sample of nearby low-mass objects including thousands of L dwarfs, hundreds of T dwarfs, and perhaps even cooler sub-stellar objects. Another project will use proper-motion measurements to improve the membership of nearby star forming regions.

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The Multiplicity of Pre–Main‐Sequence Stars in Southern Star‐forming Regions

The Astrophysical Journal ◽

10.1086/304031 ◽

1997 ◽

Vol 481 (1) ◽

pp. 378-385 ◽

Cited By ~ 171

Author(s):

A. M. Ghez ◽

D. W. McCarthy ◽

J. L. Patience ◽

T. L. Beck

Keyword(s):

Main Sequence ◽

Main Sequence Stars ◽

Star Forming ◽

Star Forming Regions

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Determination of kinematic distances of pre-main-sequence stars in star-forming regions

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309991463 ◽

2009 ◽

Vol 5 (S266) ◽

pp. 395-398

Author(s):

Phillip A. B. Galli ◽

Ramachrisna Teixeira ◽

Christine Ducourant ◽

Claude Bertout

Keyword(s):

Main Sequence ◽

Young Stars ◽

Formation Mechanisms ◽

Main Sequence Stars ◽

Star Forming ◽

Know How ◽

Star Forming Regions ◽

Moving Groups ◽

Kinematic Properties

AbstractMany studies of star-forming regions have been carried out since the discovery of compact Hii regions in the late 1960s. The kinematic properties of young stars in the nearest regions with ongoing and recent star formation provide essential tests of their formation mechanisms. The detection of coeval moving groups allows determination of individual distances through the convergent-point method. As a result, the main physical properties of these stars and their early evolutionary stages can be determined if we know how distant they are.

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The beauty of resolution: The SN Ib factory NGC 2770 spatially resolved

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314009594 ◽

2014 ◽

Vol 10 (S309) ◽

pp. 169-170

Author(s):

C. C. Thöne ◽

L. Christensen ◽

J. Gorosabel ◽

A. de Ugarte Postigo

Keyword(s):

Stellar Population ◽

Late Type ◽

Spiral Arms ◽

Star Forming ◽

Spatially Resolved ◽

Star Forming Regions ◽

The Galaxy ◽

History Of ◽

First Time

AbstractThe late-type spiral NGC 2770 hosted 3 Type Ib supernovae (SNe) in or next to star-forming regions in its outer spiral arms. We study the properties of the SN sites and the galaxy at different spatial resolutions to infer propeties of the SN progenitors and the SF history of the galaxy. Several 3D techniques are used and, for the first time, we present images of metallicity, shocks and stellar population ages from OSIRIS/GTC imaging with tunable narrowband filters.

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History of the solar environment

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309029706 ◽

2008 ◽

Vol 4 (S257) ◽

pp. 465-470

Author(s):

Kurt Marti ◽

Bernard Lavielle

Keyword(s):

Time Scales ◽

Decay Product ◽

Galactic Cosmic Rays ◽

Solar Neighborhood ◽

Iron Meteorites ◽

Spiral Arms ◽

Star Forming ◽

Star Forming Regions ◽

The Galaxy ◽

Flux Increase

AbstractGalactic cosmic rays (GCR) provide information on the solar neighborhood during the sun's motion in the galaxy. There is now considerable evidence for GCR acceleration by shock waves of supernova in active star-forming regions (OB associations) in the galactic spiral arms. During times of passage into star-forming regions increases in the GCR-flux are expected. Recent data from the Spitzer Space Telescope (SST) are shedding light on the structure of the Milky Way and of its star-forming-regions in spiral arms. Records of flux variations may be found in solar system detectors, and iron meteorites with GCR-exposure times of several hundred million years have long been considered to be potential detectors (Voshage, 1962). Variable concentration ratios of GCR-produced stable and radioactive nuclides, with varying half-lives and therefore integration times, were reported by Lavielleet al. (1999), indicating a recent 38% GCR-flux increase. Potential flux recorders consisting of different pairs of nuclides can measure average fluxes over different time scales (Lavielleet al., 2007; Mathew and Marti, 2008). Specific characteristics of two pairs of recorders (81Kr-Kr and129I-129Xe) are the properties of self-correction for GCR-shielding (flux variability within meteorites of varying sizes). The81Kr-Kr method (Marti, 1967) is based on Kr isotope ratios, while stable129Xe is the decay product of the radionuclide129I, which is produced by secondary neutron reactions on Te in troilites of iron meteorites. The two chronometers provide records of the average GCR flux over 1 and 100 million year time scales, respectively.

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Binary Frequency Among Pre-Main Sequence Stars in Taurus and Ophiuchus

Highlights of Astronomy ◽

10.1017/s1539299600007565 ◽

1989 ◽

Vol 8 ◽

pp. 117-118

Author(s):

M. Simon

Keyword(s):

Binary Systems ◽

Main Sequence ◽

Young Stars ◽

Main Sequence Stars ◽

Star Forming ◽

Lunar Occultation ◽

Star Forming Regions ◽

Powerful Means ◽

Comparable Sample

AbstractThe lunar occultation technique applied in the IR offers a powerful means of identifying binaries among obscured young stars. Our program has revealed binaries with separations from 1 to 100 AU in the Taurus and Ophiuchus star forming regions to about K=9 mag. To date, 29 objects have been observed; 6 were discovered to be binaries. The observed binary frequency is about half that expected from the binary statistics of a comparable sample of field stars. The discrepancy is probably attributable to our insensitivity to binary systems with secondary mass much less than that of the primary.

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The VMC survey – XXXIV. Morphology of stellar populations in the Magellanic Clouds

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2400 ◽

2019 ◽

Vol 490 (1) ◽

pp. 1076-1093 ◽

Cited By ~ 4

Author(s):

Dalal El Youssoufi ◽

Maria-Rosa L Cioni ◽

Cameron P M Bell ◽

Stefano Rubele ◽

Kenji Bekki ◽

...

Keyword(s):

Main Sequence ◽

Near Infrared ◽

Stellar Populations ◽

Magellanic Clouds ◽

Main Sequence Stars ◽

Spiral Arms ◽

Star Forming ◽

Star Forming Regions ◽

Tidal Interactions ◽

Using Data

ABSTRACT The Magellanic Clouds are nearby dwarf irregular galaxies whose morphologies show different properties when traced by different stellar populations, making them an important laboratory for studying galaxy morphologies. We study the morphology of the Magellanic Clouds using data from the Visible and Infrared Survey Telescope for Astronomy survey of the Magellanic Clouds system. We used about 10 and 2.5 million sources across an area of ∼105 and ∼42 deg2 towards the Large and Small Magellanic Cloud (LMC and SMC), respectively. We estimated median ages of stellar populations occupying different regions of the near-infrared (J − Ks, Ks) colour–magnitude diagram. Morphological maps were produced and detailed features in the central regions were characterized for the first time with bins corresponding to a spatial resolution of 0.13 kpc (LMC) and 0.16 kpc (SMC). In the LMC, we find that main-sequence stars show coherent structures that grow with age and trace the multiple spiral arms of the galaxy, star-forming regions become dimmer as we progress in age, while supergiant stars are centrally concentrated. Intermediate-age stars, despite tracing a regular and symmetrical morphology, show central clumps and hints of spiral arms. In the SMC, young main-sequence stars depict a broken bar. Intermediate-age populations show signatures of elongation towards the Magellanic Bridge that can be attributed to the LMC–SMC interaction ∼200 Myr ago. They also show irregular central features suggesting that the inner SMC has also been influenced by tidal interactions.

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Searching for Faint Planetary Nebulae Using the Digital Sky Survey

Publications of the Astronomical Society of Australia ◽

10.1071/as09025 ◽

2010 ◽

Vol 27 (2) ◽

pp. 156-165 ◽

Cited By ~ 40

Author(s):

George H. Jacoby ◽

Matthias Kronberger ◽

Dana Patchick ◽

Philipp Teutsch ◽

Jaakko Saloranta ◽

...

Keyword(s):

Main Sequence ◽

Total Population ◽

Accurate Estimate ◽

Close Binary ◽

Main Sequence Stars ◽

Chemical Enrichment ◽

Sky Survey ◽

The Galaxy ◽

Data Collections ◽

Galactic Planetary Nebula

AbstractRecent Hα surveys such as SHS and IPHAS have improved the completeness of the Galactic planetary nebula (PN) census. We now know of ∼3000 PNe in the Galaxy, but this is far short of most estimates, typically ~25 000 or more for the total population. The size of the Galactic PN population is required to derive an accurate estimate of the chemical enrichment rates of nitrogen, carbon, and helium. In addition, a high PN count (>20 000) is strong evidence that most main-sequence stars of mass 1–8 M⊙ will go through a PN phase, while a low count (<10 000) argues that special conditions (e.g. close binary interactions) are required to form a PN. We describe a technique for finding hundreds more PNe using the existing data collections of the digital sky surveys, thereby improving the census of Galactic PNe.

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